Absorption refrigeration and heat pump system with defrost

ABSTRACT

An integrated three-chamber absorption refrigeration and heat pump system with improved defrost capabilities having a solution pair including a material of .[.unusable.]. .Iadd.unusual .Iaddend.fluid stability at higher temperatures when manipulated in an apparatus and system to take advantage of its properties. Disclosed materials of a solution pair for operation as part of the system of this invention are ammonia as the refrigerant and sodium thiocyanate as the absorbent. A heat transfer sub-system is provided, for conveying a working fluid between the components, having multiple switchable valve means, including first, second, and third valve members selectively switchable to convey the working fluid from the cooling mode to the heating mode and vice versa, as well as to the defrost mode.

FIELD OF THE INVENTION

This invention relates to a cooling and heating system which operates onthe absorption and phase change heat exchange principle. Moreparticularly it relates to a continuous heat actuated, air cooled,multiple effect generator cycle, absorption system.

In further aspects, this invention relates to improvements to the systemconstructed for use with an absorption refrigeration solution paircomprising a nonvolatile absorbent and a highly volatile refrigerantwhich is highly soluble in the absorbent. A disclosed refrigerant pairis ammonia as the refrigerant and sodium thiocyanate as the absorbent.

BACKGROUND OF THE INVENTION

The background of this invention is found in U. S. Pat. No. 4,646,541(hereinafter the Prior Patent) which discloses the general subjectmatter of this invention. This invention therefore should be consideredwith reference to this Prior Patent which includes the common inventorsF. Bert Cook and Edward A. Reid, Jr. and is assigned to the sameassignee as this invention.

U.S. Pat. Nos. 4,742,693, 4,719,767, 4,691,532, 4,742,687, and 4,722,193are sibling patents of the Prior Patent and are pertinent to thedisclosure of this invention providing further background information onthis subject matter.

In the quest for improvement in Absorption Refrigeration and Heat PumpSystems, the common measure of performance is the often referred to"coefficient of performance", i.e., COP. As used herein, coefficient ofperformance, i.e, COP, is defined as the energy transferred at the loadin a unit of time divided by the energy provided to the system in thesame unit of time which is well understood by those skilled in the art.Other measures of performance include reduction in complexity; or statedconversely, apparatus and system simplification.

Absorption systems are usually very efficient during the heating cycle,when a source of heat, such as a natural gas flame is used. On the otherhand, these systems are less efficient in the cooling cycle.

Air cooled refrigeration circuits of the mechanical vapor compressiontype have also been demonstrated which can be reversed to provide eitherheating or cooling to a load by switching the flow of an intermediateheat transfer solution typically consisting of water and antifreezesolutions such as ethylene glycol, etc.

Liquid cooled absorption refrigeration circuits using the double effectgenerator cycle to achieve high efficiency are commercially available.However, these systems using water as the refrigerant are not suitablefor use in heating a conditioned space (the heating load) since therefrigerant freezes at 32° F. and therefore cannot be used in a spaceheating system at ambient outside temperatures below approximately 40°F.

Absorption refrigeration and heat pump systems are well known in theirbasic operating characteristics and need little further descriptionexcept to establish the definitions and context in which this inventionwill be later described.

In a typical system a refrigerant, water or other phase change materialis dissolved in an absorbent (typically lithium bromide or other salts)and these are often called the "solution pair". The refrigerant isabsorbed or desorbed (expelled) in or out of solution with the absorbentto varying degrees throughout the system and the heat of absorption isadded or extracted to produce heating and cooling effects.

The solution pair enters a generator where it is subjected to heat andthe applied heat desorbs (expels) a portion of the refrigerant in theform of a vapor which is conveyed to the condenser. There, .[.coolingexternal.]. .Iadd.external cooling .Iaddend.condenses the refrigerantvapor to liquid, which is conveyed through an expansion valve, into anevaporator where heat is gained. In the refrigeration system operationthe heat gained in the evaporator is from the cooling load.

The low pressure vapor then passes to an absorber where cooling allowsthe absorbent solution to absorb the refrigerant vapor. The solution isthen conveyed to a recuperator by a pump. The recuperator is acounterflow heat exchanger where heat from the absorbent/refrigerantsolution flowing from the generator to the absorber, heats the returningsolution pair flowing from the absorber to the generator. In the heatingcycle, the cooling applied at the absorber and/or the condenser is theheat .[.delivery.]. .Iadd.delivered .Iaddend.to the heating load.

As a matter of convenience and terminology herein, each part of theabsorption system which operates at the same pressure is termed achamber.

Conventional absorption refrigeration/heating systems are two chambersystems although three chamber systems appear in the prior art and haveseen limited use. When operated as heat pumps, two chamber systems giverespectable heating performance but give poor cooling performance.

Using ammonia (NH₃) as the refrigerant and water (H₂ O) as the sorbent,heat pumping can occur from an ambient air source which is attemperatures below freezing. Where the air is treated as if it were dryso that no defrosting is necessary, the typical two chamber NH₃ /H₂ Oheat pump would represent a significant improvement over what would beexpected of a simple furnace. However, since heat pumps are moreexpensive than furnaces, cooling season performance benefits are neededto justify the added expense. In other words, the heat pump must act asan air conditioner also to offset .[.tne.]. .Iadd.the.Iaddend.additional cost of the heat pump combined with separateinstallation of an air conditioner .[.wirh.]. .Iadd.with .Iaddend.afurnace.

For cooling, an NH₃ /H₂ O system is predicted to have a COP equal toabout 0.5. This low performance index causes unreasonable fuel (orenergy) costs from excessive fuel (or energy) use.

Three-chamber systems of various types have been suggested which wouldimprove the performance by staging the desorption process into effects.This allows for increasing the actual temperature at which the drivingheat is added to the system (cycle). Until the invention of U.S. Pat.No. 4,646,541 it was thought that this increase in temperature wouldrepresent an unreasonably high pressure, especially from ammonia/watersystems, and would force the system to operate in regions for which datais not readily available.

In addition the pressure has tended to rule out ammonia/water in athree-chamber system. The search for organic materials such ashalogenated hydrocarbons and other refrigerants as a replacement for theammonia has been limited by fluid stability at these highertemperatures. Normal organic refrigerant stability tests have indicatedthat it is necessary for oil to be present for operation in vaporcompression refrigeration systems. These high operating temperaturesrule out most of the common refrigerants, particularly from being heateddirectly by combustion products which often cause local hot spots, whichresult in working fluid degradation and/or corrosion of components.

The heat actuated, air cooled, double effect generator cycle absorptionrefrigeration system of Prior Patent (U.S. Pat. No. 4,646,541) and thesibling patents therefrom overcome limitations of the existing prior arttechnology. The air cooled system therein eliminated the need forcooling water and the use of ammonia as the refrigerant avoidsrefrigerant freezing during heating operation. The double effectgenerator cycle permits high efficiency through internal heat recoveryin the absorption refrigeration circuit. The use of sodium thiocyanateas the absorbent eliminates the need for analyzers and rectifiers topurify the refrigerant stream with the resultant loss of unrecoverableheat.

This invention is directed to further improvements and simplificationsof the above described prior patented system. It applies to anintegrated three-chamber system having one solution pair using amaterial of unusual fluid stability at higher temperatures whenmanipulated in an apparatus and system to take advantage of itsproperties. The typical preferred solution pair for operation as part ofthe system and components of this invention is ammonia as therefrigerant and sodium thiocyanate as the absorbent.

SUMMARY OF THE DISCLOSURE

In summary, this invention includes an absorption refrigeration and/orheating system in connection with a primary source of heat, a cooling orheating load, and a heat sink or secondary source, to selectivelyprovide heat to or remove heat from the load, including componentscomprising: (a) a multiple effect generator means having multipledesorber components to apply the primary source of heat to anyabsorption solution pair comprising a highly volatile refrigerant, andan absorbent to desorb refrigerant from the pair; (b) a condenser meansconnected to the multiple desorber components or the generator means;(c) an evaporator means connected to the condenser means; (d) anabsorber means connected to the evaporator means; (e) a pump meansconnected between the absorber means and the generator means to transfersolution to the generator means at higher pressure; and (f) a heattransfer subsystem for conveying a working fluid between the componentsand having multiple switchable valve means, including first, second andthird valve members selectively switchable to convey transfer fluid: (i)in the .[.one.]. cooling mode, to cool the load by directing the workingfluid between heat exchange with the condenser means, the absorber meansand a first heat exchanger in heat exchange relationship to the heatsink, while directing the working fluid between heat exchange with theevaporator means and a second heat exchanger in heat exchangerelationship with the load, and (ii) in the heating mode, to heat theload by directing the working fluid between heat exchange with thecondenser means the absorber means and the second heat exchanger in heatexchange relationship with the load, while directing the working fluidbetween heat exchange with the evaporator means, and the first exchangermeans in heat exchange with the load.

The foregoing and other advantages of the invention will become apparentfrom the following disclosure in which a preferred embodiment of theinvention is described in detail and illustrated in the accompanyingdrawings. It is contemplated that variations and structural features andarrangement of parts may appear to the person skilled in the art,without departing from the scope or sacrificing any of the advantages ofthe invention which are delineated in the included claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of the double effect absorption system of thisinvention in the cooling mode.

FIG. 2 is a diagram of the hydronic working fluid subsystem of thedouble effect absorption system of this invention in the heating mode.

FIG. 3 is a diagram as in FIG. 2 of the double effect absorption systemof this invention in the defrost mode.

FIG. 4 is a cross-sectional elevational view of the evaporator apparatusof this invention taken on the line 4--4 of FIG. 6.

FIG. 5 is a schematic elevational sectional view of one embodiment ofthe apparatus and system of this invention as it could be constructedfor installation adjacent to a building having a cooling and/or heatingload.

FIG. 6 is a schematic plan view of the embodiment of the apparatus shownin FIG. 5.

FIG. 7 is a cross-sectional elevational view of thegenerator/recuperator module of this invention taken on the verticallongitudinal axis 7--7 of FIG. 5.

FIG. 8 is a elevational perspective view of the separator components ofthis invention.

FIG. 9 is a schematic cross-section elevational view of theabsorber/condenser module of this invention with auxiliary components.

FIG. 10 is a schematic diagram of one embodiment of the energy recoveryapparatus arrangement of this invention.

FIG. 11 is a schematic diagram of one embodiment of the energy recoveryapparatus arrangement of this invention.

FIG. 12 is a schematic view of an alternative energy recovery unitincluded in this invention.

FIG. 13 is a schematic view of an alternative addition to the system ofthis invention for the purpose of providing domestic hot water.

DETAILED DESCRIPTION OF A BEST MODE OF PREFERRED PRACTICE OF THEINVENTION

In the description of this invention, it is important that there is aclear understanding of the meanings of the terms used herein. Otherwise,because of the complexity of the entire system and the use of componentsfrom various fields of mechanical, chemical, and electrical arts, theterminology could be confusing in some cases.

Therefore, as used herein the term "strong solution", when speaking ofthe solution pair refers to that solution that has picked up refrigerantin the absorber and is in progress toward the generator and carries ahigher ratio of refrigerant to absorbent than solution which has beendesorbed and partially expelled of refrigerant in the generator(s) ofthe system. Solution from which refrigerant has been expelled is, bycontrast, a "weak" or weaker solution holding a lesser ratio ofrefrigerant to absorbent in solution.

In the three chamber system of this invention, a solution of"intermediate" strength is employed between the generator means. Thissolution is by definition, weaker than strong solution and stronger thanweak solution.

The terms "generator" and "desorber" are synonymous. The term "heatexchanger" defines apparatus where fluids are passed in close proximityto each other separated only by a usually impervious wall through whichthe heat from the warmer is conducted to the cooler. Conventionally, itis understood that heat passes from the hot fluid to the cold fluid.

As used herein, the term "heat exchanger" defines an apparatus whichexchanges heat into or out of the system; i.e., with an external fluidsuch as ambient outdoor air, or ground water, or working fluid. Thoseapparatus which exchange heat within the system are termed"recuperators".

As further used herein, the term "working fluid" defines the fluid usedto transfer heat to or from the load or heat sink. Preferably this is anethylene glycol and water solution which is capable of remaining anunfrozen liquid at temperatures colder than liquid water alone. However,other working fluids such as calcium chloride and water could also beused.

As described in the Background Of The Invention portion of thisdisclosure, a double effect generator absorption system in which thethermo/physical properties are enhanced by the application of a sodiumthiocyanate/ammonia absorbent/refrigeration pair, with generator andheat exchanger in a stacked coil configuration including tube-in-tubeconcepts, together with the combination of energy recovery motors tocontribute to the power requirement of the solution pump required andfound in absorption refrigeration systems, form the basis for theimprovements to be further described below. Although sodiumthiocyanate/ammonia are the preferred absorbent/refrigerant pair, otherabsorbents and refrigerants can be used including methyl or ethyl amineas the refrigerant and alkali metal nitrates or thiocyanates as theabsorbent.

While the invention therein is a quantum leap forward in the applicationof methods and the construction of apparatus of heat driven absorptionrefrigeration and heat pump systems, and in particularly through theselection of the solution pair "ammonia as the refrigerant and sodiumthiocyanate as the sorbent", it has been found that various improvementswill be made with the methods and apparatus of this invention.

DOUBLE EFFECT GENERATOR ABSORPTION SYSTEM WITH SWITCHING BETWEENCOOLING, HEATING, AND DEFROSTING

An absorption heat pump conceived to provide both space heating andspace cooling must be able to be reversed between the heating and thecooling modes without adversely effecting the operation of theabsorption refrigeration cycle. It is conceived in this invention thatthe double effect absorption heat pump shall remain operating in thesame manner and in the same apparatus components for both the heatingand cooling modes of operation. This method and apparatus of operationis uniquely conceived in connection with the application of surprisinglyeffective heat transfer components and methods provided in an improvedgenerator/recuperator apparatus and in an improved condenser/absorbercombination to be further described in detail as follows. Thearrangement of working fluid switching valves and control components arecontributing features in the invention.

Referring to FIG. 1 a first generator means 80 feeds a heated strongsolution 83 to a first separator 91. In the first generator means 80 andthe separator 91, a vapor refrigerant 82 is desorbed and separated bythe application of heat from a source 84, such as a gas flame.

A preferred construction of the first generator means 80 is shown inFIG. 7.

A solution of intermediate strength 85 remains in separator 91 and isconveyed to a first recuperator means 86 and then through a throttlingvalve or energy recovery motor 87 to a second generator means 81. Heatfrom the refrigerant vapor 82 is exchanged with the intermediatesolution 85 in the second generator 81. Additional vapor 82 is desorbedfrom the intermediate solution 85 leaving a weak solution 89 in a secondseparator 92.

The weak solution 89 passes through a second recuperator 95 and athrottling valve 96 with a connection at 93, and into an absorber means97. The weak solution 89 absorbs vaporous refrigerant 82 becoming astrong solution 83 which is pumped by a solution pump 98 successivelythrough recuperators 95 and 86 back to the first generator means 80.

Liquid refrigerant 82 is conveyed from the .[.separator 91.]..Iadd.second generator 81 .Iaddend.through an .[.expansion valve or.].energy recovery motor .Iadd.or expansion valve .Iaddend.105, and througha condenser 100 by way of a connection 94. Additional refrigerant vapor82 from separator .[.91.]. .Iadd.92 .Iaddend.is conveyed to thecondenser 100 through the connection 94.

From the condenser 100 liquid refrigerant 82 is conveyed through a thirdrecuperator 107, to an evaporator 115, by way of an expansion valve 110.

Cool low pressure refrigerant is returned from the evaporator 115through the recuperator 107, exchanging heat with the warm liquidrefrigerant 82, and passing to an accumulator 205.

In the accumulator 205, excess refrigerant 82 is collected which mayhave occurred as a result of changes in the amount of refrigerantcontained in the condenser 100 and evaporator 115 because of theiroperation at different conditions, especially differences betweencooling, heating, and defrost modes of operation. By this arrangement,the system refrigerant concentration may ideally be controlled betweenabout 46% and about 32%.

From the accumulator 205 refrigerant joins the weak solution 89 at theconnection 93. From the connection 93 the combined weak solution andrefrigerant pass through the absorber 97 to a purge pot 99 thence to theinlet of a solution pump 98. By this process weak solution 89 absorbsvaporous refrigerant 82 becoming a strong solution 83 in the absorber97, and is pumped by a solution pump 98 back to the first generatormeans 80, passing successively through recuperators 95 and 86.

This improvement invention includes a separate hydronic subsystemthrough which a working fluid is conveyed among the various componentsof the double effect absorption refrigeration system, and between theload and heat source or sink.

Referring again to FIG. 1, the subsystem is depicted as a single fineline, which is connected to the inlet .Iadd.113 .Iaddend.of thecondenser 100 and passes through to a first four-way fluid valve 101which is set to continue the flow to the inlet 103 of the absorber 97.After passing through the absorber 97, the fluid is conveyed from anoutlet 104 to a second four-way valve 106, and fed to an inlet of afirst outdoor heat exchanger 108. From the first heat exchanger 108 theworking fluid is conveyed through a pump 109 to a third four-way valve112 which has been positioned to return the working fluid to an inlet113 of the condenser 100. By means of these connections, the heat ofcondensation and absorption of the hot refrigerant 82 is exchanged tothe working fluid in the condenser 100 and absorber 97 which transferthe heat through the working fluid to the ambient outside air by heatexchange in the first heat exchanger 108. A fan 114 induces air flowacross the first heat exchanger 108 increasing the rate of heat exchangeto the outside ambient air.

In this cooling mode operation, the outlet 104 of the absorber 97 isconnected from a joinder 116 through the first four-way valve 101 to theinlet 118 of the evaporator 115 at a joinder 117. No flow takes placebetween the joinders 116 and 117 in this mode, because there is nodifferential pressure in the working fluid between these two points andthere is no return path. Therefore, flow cannot occur.

In this mode of operation, the working fluid is conveyed from an inlet118 through the evaporator 115 to an outlet 119. From the outlet 119 ofthe evaporator 115, the working fluid is conveyed to four-way valve 106and thence to the indoor second heat exchanger .[.121, via valve 106.]..Iadd.121 .Iaddend.where air from the conditioned space passes in heatexchange relationship with the working fluid. A fan 122 induces air flowacross the coils of heat exchanger 121.

From the indoor heat exchanger .[.12!, .Iadd.121, .Iaddend.the workingfluid is conveyed by a pump 123 past the joinder 117 and through thethird valve 112 to the inlet 118 of the evaporator 115.

In this mode of operation the working fluid is cooled as it passes inheat exchange relationship with the cooled refrigerant in the evaporator115. The cooled working fluid transfers this cooling to the indoorconditioned air in the second indoor heat exchanger 121.

Referring to FIG. 2, the double effect generator absorption system andoperation remains the same for the heat pumping mode. However in thisheating mode, the working fluid subsystem is switched by means ofchanges in the position of four-way valves 106 and 112. The four-wayvalve 101 remains in the previous position as shown for the cooling modeof FIG. 1.

In this arrangement the hot working fluid from the condenser 100 isconveyed through outlet 102 and four-way valve 101 to the inlet 103 ofthe absorber 97. The subsystem provides cooling to the absorber becausethe combined refrigerant and weak solution are at higher temperature, sothat the necessary absorption process takes place in the absorptionrefrigeration system. The working fluid is heated further thereby andleaves the absorber 97 by way of outlet 104 to the four-way valve 106which is reversed from the previous cooling mode of operation. Theworking fluid now passes to the second heat exchanger 121 where itexchanges heat with the conditioned air of the living space (the load).Being cooled from the air in the living space, .[.valve 112.]..Iadd.pump 123 .Iaddend.directs the working fluid back through .[.pump123.]. .Iadd.valve 112 .Iaddend.to the inlet 113 of the condenser 100.

In this normal heating mode position of the four-way valves 106 and 112,the working fluid is conveyed from the evaporator 115 through theoutdoor heat exchanger 108 where it receives heat from the outdoor airbefore returning to the evaporator inlet 118. The fan 114 may beoperated intermittently depending on the outdoor air temperature andhumidity conditions to reduce frost build up on the heat exchangesurfaces. When the subsystem valves 106 and 112 are operating in thisposition, heat pumping occurs from the outside air to the evaporatorraising the temperature of operation of the subsystem providing for atheoretical COP of higher than .[..]. .Iadd.1.0. .Iaddend. Actualperformance has exceeded .Badd.0.8 with outside air temperatures ofabout 93° F. on a three ton 34,700 BTU output unit..]..Baddend.

It will be seen that in comparison to the system described in the PriorPatent, simplification and important reductions in first costs andoperating reliability have been achieved.

When the system is operating in the heating mode the first outdoor heatexchanger 108 is in communication with the evaporator and is absorbingheat from the surrounding outside ambient air environment. Under certainconditions of outside temperature and humidity the exterior surface ofheat exchanger 108 will accumulate frost from the moisture in thesurrounding atmosphere. An accumulation of frost on the surfaces of theoutdoor heat exchanger 108 reduces its heat exchange efficiencyhindering heat pumping operation and reducing the overall systemperformance. Various solutions have been proposed and are used in priorpractices to overcome this problem, such prior systems are inconvenientand draw down the COP of the unit by the requirement of additional heatenergy, such as by electrical resistance or the requirement for anauxiliary boiler.

However, in the operation of the system of this invention, defrosting isaccomplished when four-way valves 112 and 101 are reversed and four-wayvalve 106 remains as positioned for the heating mode. Air flow acrossthe .[.second.]. .Iadd.first .Iaddend.heat exchanger 108 is interruptedby shutting off the fan 114. The warm working fluid from the condenseris directed through the heat exchanger 108 melting the frost. Heat fromthe absorber continues to be directed through the second indoor heatexchanger 121 providing heat to the conditioned space althoughtemporarily at a reduced rate for a short time. It is a feature of thisinvention that heat continues to flow to the load from the absorber 97during the defrost cycle. In the conventional arrangements that havebeen provided to answer the frosting problem of air transfer heat pumps,it is a practice to cut off the heat pump completely and use electricalresistance heaters to provide heating during defrosting. This inventionto the contrary, maintains heat flow from the heat pump duringdefrosting and in most circumstances, defrosting can be completed beforeheat is required in excess of that available during defrost operation.At the end of the defrost cycle, all the working fluid reversing valvesare returned to their normal heating mode position, and the air flowover the first heat exchanger 108 is restored.

Conventional controls are provided to sense the loss of efficiencyresulting from frost build-up and the defrost cycle is operatedautomatically.

As an alternative, the working fluid from the absorber 97 may be passedthrough a heat exchanger relationship with a storage tank for domestichot water when all the heat of the absorber means is not needed at theload, for instance when the outside ambient air is not cold or thesystem is operating in the cooling mode.

As shown in FIG. 13, a domestic hot water heater and tank 370 is locatedwithin the residence to which the heat pump system of this invention isinstalled. The outlet 104 of the absorber 97 is connected to an inlet371 of a heat exchange coil 372 in the hot water heater 370. An outletof coil 372 is connected to the inlet of the absorber 97. A secondsource of heat 375 such as a gas burner is also provided to the hotwater tank 370.

This domestic hot water heating subsystem is included in combination totake advantage of the excess heat available at the .[.desorber.]..Iadd.absorber .Iaddend.under circumstances where the full heatingcapacity of the system is not required for the ambient conditions beingserviced by the load. Such excess heat may be available in either thecooling .Iadd.mode .Iaddend.or heating .[.modes.]. .Iadd.mode.Iaddend.when the system is not loaded to its designed capacity. Inthose circumstances when the system is not operating or there is noexcess heat available at the absorber 97, the auxiliary burner may beoperated to assure that there is the required domestic hot wateravailable.

A LIVING SPACE ENVIRONMENTAL CONDITIONING APPARATUS

A configuration for a living space, residential air conditioning andheating embodiment of this invention is shown in FIGS. 5 and 6, in whichan air conditioning and heating unit 165 is located outside a residenceand constructed in rectangular format on a base 167, and includes ahousing 166. The housing 166 includes an upper aperture 169. Theaperture is positioned above an ambient air inductive means such as thefan 114 (See FIG. 1). .Iadd.The generator/recuperator means 220 islocated below aperture 169. .Iaddend.The first heat exchanger 108comprises three sides of the unit 165. Conveniently positioned as shownon the fourth side, are the solution pump 98, purge pot 99, evaporator115, condenser 100, absorber 97, and recuperator .[.105..]. .Iadd.107..Iaddend.The separators 91 and 92 (as shown in FIG. 8 in longitudinallyvertical position) are positioned nearby. Pumps 123 and 109 forconveying the working fluid are juxtaposed to the solution pumps 98 and157. The second heat exchanger 121 and the fan 122 are located withinthe living space.

DOUBLE EFFECT GENERATOR AND RECUPERATOR APPARATUS

Referring to FIGS. 5, 6, and 7, an embodiment of a double effectgenerator/recuperator means 220 is shown as apparatus which integratesin one interrelated assembly the various components and modules that areassociated with the use of the heat generated in a heat source 84. Tofacilitate understanding, numerical designations are the same as andrefer to like components in the system shown in FIG. 1.

Generator Module

As shown in FIG. 7, a generator unit or module 220 is generallysymmetrically constructed about a substantial vertical central axis.Generator module 220 includes a generator housing 221 that may becircular in the plan view (FIG. 6) and which is constructed on agenerator frame base 222 that may be the same or distinct from the base167 of the heating and air conditioning unit .[.165..]. .Iadd.165 (FIGS.5 and 6). .Iaddend.Generator unit 220 contains a circular floor 230attached to the generator housing 221 above the generator base 222 so asto contain insulating material 231. Generator floor 230 slopes gentlyfrom the center to the generator housing 221 so as to allow for thedrainage of condensed moisture from the unit.

The generator housing 221 includes an upper generator shroud 223 and agenerator ceiling 224 between which is placed insulating material 225. Acylindrical passage 226 is formed by a cylinder 227 joining the centerportion of the shroud 223 and the center portion of the generatorceiling 224. A cylinder cap 228 seals the cylinder 227 from thesurrounding atmosphere and provides a mounting surface to whichgenerator blower 229 is attached. Cylinder cap 228 contains an aperture(not shown) that allows air from the blower 229 to enter the generatorunit 220 through cylindrical passage 226.

A central driving heat source 84 providing external heat to the system,typically a gas burner, is centrally positioned substantially on acentral axis 232 of unit 220. A gas source is not shown but it is to beunderstood to be of conventional piping design. Annular componentssurround the circular heat source 84 and include a first generator means(desorber means) 80, a first (high-temperature) recuperator means 86, asecond generator means 81, and a second (low-temperature) recuperatormeans 95. Each component is constructed as a plurality of coils,juxtaposed one to the next, in a substantially or generally annularcomposite form i.e, vertically positioned toruses or helices. Componentsare juxtaposed one to the next, and radially more or less distant fromthe central axis 232, i.e., surrounding the source of heat 84 at varyingdistances. The generator 80 coils have fine fins that allow for thepassage of hot gases between and among the coils so as to achievemaximum heat transfer. See, for example FIG. 5 item 200 of U.S. Pat. No.4,742,693 which is herein incorporated by reference. First and secondrecuperators and the second generator have coils with a solid exteriorsurface that are wound in contact with each other.

The recuperators, 86 and 95, and second generator 81, have an inner tubeand an outer tube arranged in what is often referred to as tube-in-tubeconstruction. Preferably the inner tubes have helical flutes 233 tobetter effect heat transfer between the fluids in the inner and outertubes. Fluted tubes are available commercially from suppliers such asTurbotec Products, Inc., Windsor, Conn. and Delta-T Limited, Tulsa,Okla. The liquid-liquid heat exchangers and absorbers have three flutes.Evaporators and condensers have four flutes and about three times asmany flutes per foot. That is, not only do the evaporators andcondensers have more flutes but they also are twisted more revolutionsper foot.

Tubing materials are conventional, being chosen for good heat transferthrough the walls of the tubing and corrosion resistance. Metals such asstainless steel and low alloy steels such as AISI 9260 and AISI 1075 aresuitable. Generator 80 is typically of conventional single tubeconstruction with small, fine fins.

In the preferred embodiment shown in FIG. 7, high-temperature air andcombustion products (flue gas) 245 are generated in a first generatorchamber and impinge upon the walls 131 of the tubular generator 80 beingdriven more or less downward and radially outward direction through thefins between the coils of generator 80 by blower 229. The hot combustionproducts 245 emerge through apertures 235 in cylindrical baffle 234 andflow downward along the solid inner cylindrical first recuperatorhousing .Iadd.baffle .Iaddend.236 where they emerge through apertures238 in the bottom of inner recuperator housing 236.

The hot air and combustion products 245 then enter a second(recuperator) chamber 237 surrounding the first generator chamberthrough apertures .[.238.]. .Iadd.268 .Iaddend.in the bottom housing 250of the first recuperator chamber 237. The hot air and combustionproducts 245 impinge upon the coils of tube 249 of the first recuperator86 while flowing in a generally upward direction. The warm combustionproducts and air 245 emerge into a third or outer chamber 240 of thegenerator unit from the second chamber 237 through apertures 312 locatedin the top portion of the outer recuperator housing 239. The warmcombustion products and air 245 impinge upon the coils of tube 252 ofthe second generator 81 and the coils of tube 260 of the secondrecuperator 95 while flowing in a generally downward direction.Combustion products and air 245 emerge from the generator unit 220through apertures 241 in the generator housing 221 located just abovethe generator floor 230.

The generator, recuperator, and other chambers are concentriccylindrical chambers juxtaposed one to the next. The general flow ofcombustion products and air is indicated by arrows in FIG. 7 as beinggenerally in a serpentine fashion, i.e. downward in the first chamber,upward in the second chamber, and downward in the third chamber.

The first generator means 80 is made from a finned double-wound helicalcoil of tubing. Strong solution 83 enters the first generator 80 fromthe first (high temperature) recuperator 86 through inlet 137 at atemperature of about 385° F. and a pressure of .[.1480.]. .Iadd.1490.Iaddend.psia. The strong solution 83 is heated by the heat source 84 asit flows downward through the outer winding of helical coil and thenupward through the inner winding of the helical coil emerging from thefirst generator means 80 through outlet 138 at a temperature of about415° F. The strong solution 83 receives direct heat from the heat source84 at a rate of about 36,000 btu/hr.

As shown in FIGS. 1 and 8, the heated strong solution 83 then enters thefirst (primary) separator 91 through separator inlet 242 where itseparates into intermediate solution 85 and refrigerant vapor 82. Theintermediate solution 85 leaves separator 91 through lower outlet 243.The refrigerant vapor 82 leaves separator 91 through upper outlet 244.

Returning to FIG. 7, the intermediate solution 85 enters the firstrecuperator 86 through inner fluted-tube inlet 246. First recuperator 86consists of three rows of a fluted tube-in-tube helical windings locatedradially outwardly adjacent to first generator 80 and extendingvertically for almost the length of the first generator 80. The firstrecuperator 86 is contained in the cylindrical first recuperator chamber237 that is formed by inner cylindrical baffle 236, outer cylindricalrecuperator housing 239, the generator unit ceiling 224 and firstrecuperator housing bottom 250. As the intermediate solution 85 passesthrough the fluted inner tube 248 of recuperator 86, it exchanges heatto the strong solution 83 in the outer tube 249 of the recuperator 86 ata rate of about 69,000 btu/hr and leaves through the inner tube outlet247 at a temperature of 245° F. and a pressure of 1450 psia.Intermediate solution 85 is then throttled substantially isenthalpicallythrough valve 87 (FIG. 1) and arrives at the secondary generator 81 at atemperature of 245° F. and a pressure of 290 psia.

The intermediate solution 85 enters the second generator means 81through outer tube inlet 251. The second generator 81 consists of tworows of fluted tube-in-tube helical windings located radially outwardlyadjacent to first recuperator 86 and extending vertically along the topportion of the first recuperator 86. The second generator 81 iscontained in the upper portion of the cylindrical outer-mostgenerator-unit chamber 240 that is formed by the outer .Iadd.cylindrical.Iaddend.first recuperator housing 239, the generator unit housing 221,the generator unit ceiling 224 and the generator unit floor 230. As theintermediate solution 85 passes through the outer tube 252,approximately 18,000 btu/hr is transferred to it from the condensingrefrigerant vapor 82 in the inner fluted tube 253. About an additional1,000 btu/hr is transferred to the intermediate solution 85 in the outertube 252 from the circulating flue gases 245. The intermediate solution85 leaves the second generator 81 through second generator outer tubeoutlet 254 at a temperature of 255° F. and a pressure of 290 psia.

As shown in FIGS. 1 and 8, the heated intermediate solution 85 thenenters the second (secondary) separator 92 through separator inlet 255where it separates into weak solution 89 and refrigerant vapor 82. Theweak solution 89 leaves separator 92 through lower outlet 256. Therefrigerant vapor 82 leaves separator 92 through upper outlet 257.

Weak solution 89 leaves the separator 92 at a pressure of 290 psia and atemperature of 255° F. and enters the second recuperator 95 throughsecond recuperator inner fluted-tube inlet 258. The second recuperator95 consists of two rows of fluted tube-in-tube helical windings locatedradially outwardly adjacent to first recuperator 86 and extendingvertically along the lower-upper and lower portions of the firstrecuperator 86. The second recuperator 95 is contained in the lowerupper and lower portions of the cylindrical outer-most generator-unitchamber 240 that is formed by the outer first recuperator housing 239,the generator unit housing 221, the generator unit ceiling 224 and thegenerator unit floor 230. As the weak solution 89 passes through thefluted inner tube 259 of the second recuperator 95, it transfersapproximately 50,000 btu/hr to the strong solution 83 in outer tube 260as the strong solution 83 is on its way to the first recuperator 86. Theweak solution leaves the second recuperator 95 through the innerfluted-tube outlet 261 and is then throttled substantiallyisenthalpically through valve 96 (FIG. 1) and arrives at connection 93at a temperature of 120° F. and a pressure of 70 psia.

High pressure vapor 82 from the upper outlet 244 of separator 91 entersthe second generator 81 through inner fluted-tube inlet .Iadd.262.Iaddend.at a temperature of 415° and pressure of 1480 psia. Whilecirculating through fluted inner tube 253, the vapor is condensedliberating approximately 18,000 btu/hr to the intermediate solution 85in outer tube 252. The condensed vapor 82 leaves the second generator 81through inner fluted-tube outlet .Iadd.263 .Iaddend.at a temperature ofabout 260° F. Passage of the condensed vapor 82 through expansion valve.[.110.]. .Iadd.105 (FIG. 1) .Iaddend.reduces its temperature to 120° F.and its pressure to 290 psia. The expanded vapor 82 is joined with thevapor 82 from the secondary separator 92 at connection .[.94..]..Iadd.94 (FIG. 1)..Iaddend.

After the vapor 82 is absorbed into the weak solution 89 in the absorber97 and the resulting strong solution 83 passes through the purge pot 99and pump 98, it enters the secondary recuperator 95 at a temperature of120° F. and a pressure of 1550 psia through outer tube inlet 264. Whilecirculating through the outer tube 260, the strong solution receives50,000 btu/hr from the weak solution 89 in the inner fluted tube 259 andan additional 1,000 btu/hr from the circulating flue gases 245. Onleaving the secondary recuperator 95 through outer tube outlet 265, thestrong solution 83 is at a temperature of 230° F. and a pressure of 1520psia.

From the secondary recuperator 95, the strong solution enters theprimary recuperator 86 through outer tube inlet 266. While circulatingthrough the outer tube 249, the strong solution 83 receives 69,000btu/hr from the intermediate solution 85 circulating in the fluted innertube 248 and an additional 1000 btu/hr from the circulating flue gases245. The strong solution 83 leaves the primary recuperator 86 throughouter tube outlet 267 at a temperature of 385° F. and a pressure of 1490psia.

Although the preferred embodiment is shown and described, otherarrangements may be suitable for different operating conditions. Forexample, the solutions within fluted tubes and that in the annulus maybe switched one for the other, especially in the low temperaturerecuperator 95 where it might be preferable not to have the higherpressure fluid in the annulus.

Absorber and Condenser Module

Referring to FIG. 9, an integrated absorber/condenser module providesfor the assembly of condenser 100 and absorber 97 components that areschematically shown in FIGS. 1-3. The absorber/condenser moduleintegrates in one interrelated assembly the various components of theapparatus that are associated with the use of the heat generated in thedriving heat source 84 for heating, cooling and defrosting.

It is to be noted that the primary (refrigerant) system, usingpreferably an ammonia/sodium thiocyanate refrigerant pair, is completelycontained in the outside heating and air conditioning unit 165 andoperates in continuous fashion without the switching of flows among thevarious components. The working subsystem, using preferably awater/glycol working fluid, transfers heat among the load (insidespace), ambient outside air, and outside heat exchanger depending onwhether the system is operating in a heating, cooling or defrostingmode.

Heat exchange between the refrigerant system and the hydronic workingfluid subsystem occurs in the absorber/condenser module 270 andspecifically in the absorber 97 and the condenser 100. Theabsorber/condenser module consists of an absorber 97, a purge pot 99, acondenser 100 and a third (tertiary) recuperator means 107. The.[.condenser 100 and the.]. tertiary recuperator 107 .[.are.]. .Iadd.is.Iaddend.preferably fluted tube-in-tube construction. The absorber 97.[.is.]. .Iadd.and condenser 100 are .Iaddend.of fluted tube-in-cylinderconstruction.

The purge pot 99 is centrally positioned substantially on a central axis271 of the annular components including the absorber 97, condenser 100and the third recuperator 107. Each component is constructed as asubstantially annular coil, or coils and/or plurality of verticallypositioned toruses or helical tubings. The absorber 97 and the thirdrecuperator 107 are juxtaposed to the condenser and are radially moredistant from the central axis 271.

The absorber/condenser module 270 is contained in cylindrical housing278 with a bottom 279 and top 280. Insulation 281 is provided betweenthe cylindrical housing 278 and the outer most components.

The absorber 97 consists of two windings of fluted tube enclosed in acylindrical space 276 formed by outer cylindrical absorber wall 284,outer condenser wall 285, absorber bottom 286 and absorber top 287. Theinner and outer windings are separated by cylindrical baffle 289. Baffle289 is attached to absorber top 287. Generally a winding may beconsidered as a plurality of coils juxtaposed one to the next in agenerally annular composite form, i.e., a cylindrical helix.

Weak solution and refrigerant mixture enter the outer winding of flutedtube 288 at the top of the absorber, flow generally downward and thengenerally upward in the inner winding, i.e. in directions generallyparallel to the axis of the absorption coils. Working fluid .[.275.].enters cylindrical space 276 through inlet 103 and circulates generallydownward and through and among the spaces formed by the juxtaposedfluted-tube outer windings. The working fluid .[.275.]. passes beneaththe lower edge of baffle 289 and then circulates generally up andthrough and among the spaces formed by the juxtaposed fluted-tube innerwindings. The working fluid leaves absorber 97 through outlet 104.

Weak solution 89 meets the refrigerant 82 at connection 93 and entersthe absorber 97 through fluted inner-tube inlet 272 at a temperature ofabout 144° F. and a pressure of about 70 psia. The refrigerant 82 isabsorbed into the weak solution 89 with release of an absorption heat of52,000 btu/hr to the working fluid .[.275.]. circulating in cylindricalspace 276. Strong solution 83 leaves the absorber 97 through flutedinner-tube outlet 277 at a temperature of about 118° F. and a pressureof about 70 psia.

After leaving absorber 97, strong solution 83 enters purge pot 99through inlet 282 and exits the purge pot through outlet 283. The purgepot is used to .[.periodically.]. remove .Iadd.periodically.Iaddend.non-condensable gases formed in the system through the ventline 310 and valve 311.

Preferably, the condenser 100 comprises a single winding of fluted tube293 i.e., a plurality of coils juxtaposed one to the next in generallyannular composite form, extending the vertical length of theabsorber/condenser unit 270 and enclosed in the cylindrical condenserspace 290 formed by inner cylindrical condenser wall 291, outercylindrical condenser wall 285, absorber/condenser top 287 and condenserbottom 292 i.e., tube-in-cylinder construction. Although less preferred,tube-in-tube construction .[.my.]. .Iadd.may .Iaddend.also be used. Iftube-in-tube construction is used, the working fluid preferablycirculates in the outer tube.

Hydronic working fluid enters the condenser space 290 through inlet.[.102,.]. .Iadd.113, .Iaddend.circulates around and through the spacesformed by the juxtaposed coils of fluted tube 293 in a directiongenerally parallel to center line 271 (in cross flow to the flow ofvapor 82 in tube 293) and leaves through outlet .[.113..]. .Iadd.102..Iaddend.Refrigerant vapor 82 enters the condenser 100 through inlet 294at a temperature of 120° F. and pressure of 290 psia. Vapor 82 condensesin fluted tube 293 transferring a condensation heat of 27,000 btu/hr tohydronic working fluid .[.275.]. circulating in condenser cylindricalspace 290. Condensed refrigerant vapor 82 leaves the condenser throughoutlet 295 at a temperature of 100° F. and a pressure of 290 psia.

The third (tertiary) recuperator means 107 is a single flutedtube-in-tube winding juxtaposed radially outward from condenser 100.Condensed vapor 82 from condenser outlet 295 enters the tertiaryrecuperator 107 through fluted-tube inlet 296 and circulates throughinner fluted tube 297 where it transfers 610 btu/hr to vapor 82 in theouter tube 298. Condensed vapor 82 leaves tertiary recuperator 107through fluted-tube outlet 299 at a temperature of 90° F. and a pressureof 285 psia.

.[.As shown in FIG. 4, evaporator 115 is a cylindrical unit with acylindrical outer housing 300, a cylindrical inner housing 301, a top303 and a bottom 304 forming cylindrical space 302. An annular windingof fluted tube 305 is contained in cylindrical space 302. Hydronicworking fluid 275 enters the evaporator 115 through inlet 118 andcirculates generally downward over, through and among the spaces formedfrom the juxtaposed windings of fluted tube 305. The hydronic fluid 275leaves the bottom of evaporator 115 through outlet 119..].

After leaving the tertiary recuperator 107, condensed vapor 82 passesthrough expansion value 110 after which it enters evaporator 115 at apressure of 72 psia and a temperature of about 39° F. through evaporatorinlet .[.307..]. .Iadd.306. .Iaddend.The condensed vapor 82 evaporatesin fluted tube 305 absorbing 36,000 btu/hr from the circulating hydronicworking fluid in evaporator cylindrical space 302. The evaporated vapor82 leaves evaporator 115 through outlet .[.306.]. .Iadd.307 .Iaddend.ata temperature of about 53° F. and a pressure of about 72 psia.

After leaving the evaporator, the refrigerant vapor 82 enters thetertiary recuperator 107 through outer tube inlet 308, circulatesthrough outer tube 298 receiving 610 btu/hr from the condensed vapor 82in inner fluted tube 297, and leaving by outer tube outlet 309 at atemperature of about 67° F. and a pressure of about 71 psia. Afterleaving the tertiary recuperator, vapor 82 enters accumulator 205.

.Iadd.As shown in FIG. 4, evaporator 115 is a cylindrical unit with acylindrical outer housing 300, a cylindrical inner housing 301, a top303 and a bottom 304 forming cylindrical space 302. An annular windingof fluted tube 305 is contained in cylindrical space 302. Hydronicworking fluid enters the evaporator 115 through inlet 118 and circulatesgenerally downward over, through and among the spaces formed from thejuxtaposed windings of fluted tube 305. The hydronic fluid leaves thebottom of evaporator 115 through outlet 119. .Iaddend.

Although the preferred embodiment is shown and described, otherarrangements may be suitable for different operating conditions. Forexample, the solutions within fluted tubes and that in the annulus maybe switched one for the other, especially in the low temperaturerecuperator 95 where it might be preferable not to have the higherpressure fluid in the annulus. The third recuperator 107 could also bemounted on the outside of the evaporator coil 115 in a fashion similarto the way it is shown as on the outside of the condenser 100. The purgepot 99 need not be inside the absorber/condenser. The chosen locationhowever does conserve space. An expansion tank to allow for expansionand contraction of the heat transfer fluid (ethylene glycol/water) couldsimilarly be placed inside the evaporator.

    ______________________________________                                        HYDRONIC WORKING FLUID TEMPERATURES                                                            INLET    OUTLET                                              ______________________________________                                        Condenser          105 °F.                                                                           110 °F.                                  Absorber           110        120                                             Evaporator          55         45                                             Outdoor Heat Exchanger                                                        Heating Mode        40         45                                             Cooling Mode       120        105                                             Indoor Heat Exchanger                                                         Heating Mode       120        105                                             Cooling Mode        45         55                                             ______________________________________                                    

SOLUTION PUMP AND ENERGY RECOVERY APPARATUS

In the operation of the absorption refrigeration system of thisinvention a mechanical energy input is necessary in addition to thethermal energy input. The necessary mechanical energy is primarilyrequired for operation of the solution pump which circulates thesolution pair through the system. In FIGS. 1, 2, and 3 the solution pump98 is shown conveying the strong solution from the absorber 97 to thefirst generator means 80 by way of the second and first recuperators 95and 86 respectively. In a system capacity of 36,000 BTU per hour, themechanical energy required to raise the solution pressure to about 1200PSIA is approximately 670 watts. Providing this mechanical energy usinga convention electric motor and pump would require consumption ofapproximately 1200 watts of electrical power which would reduce therefrigeration cycle efficiency (COP) by approximately 11%. The PriorPatent describes an energy recovery system for recovering energy fromthe isenthalpic throttling valves required for the system.

In this invention, an alternate energy recovery system has been furtherrefined as shown in FIGS. 10 and 11.

In FIG. 10, one embodiment of the improved energy recovery apparatusincludes rotary motor means 152 driving a solution pump means (which maybe either rotary or reciprocating) 98 receiving strong solution from thepurge pot 99. The solution pump 98 raises the strong solution to an.Iadd.intermediate pressure .Iaddend.and conveys the solution to asecond higher pressure solution pump 157, where the pressure is raisedto the high pressure requirements of the system before conveying thestrong solution through recuperators 95 and 86 to the first generator80.

The second pump 157 may be located between low temperature recuperator95 and high temperature recuperator 86, (shown in .[.phamton 370)..]..Iadd.phantom in FIG. 1 as 157'). .Iaddend.In that way both the pump.[.158.]. .Iadd.157 .Iaddend.and motor(s) .[.157, 158,.]. .Iadd.158.Iaddend.and 159 would all be at more nearly equal temperatures. Also,both pipes of the low temperature .Iadd.recuperator 95 .Iaddend.would beat more nearly equal pressures--significantly lower than the primarygenerator pressure.

The solution pump 157 is driven by energy recovery means 158 and,alternatively, also by additional energy recovery means 159.

Solution pump 98 is preferably an electric motor driven pump ofconventional design. Solution pump 157 may be either a rotary pump or areciprocating pump more suitable for high pressure service, being drivenby reciprocating expansion devices operating through the pressure letdown of the expansion means 87 and 105.

In the construction according to FIG. 10, the energy recovery motors arenot mechanically connected to the shaft of the motor 152 providing moreflexibility in the operation of the solution pump and energy recoveryarrangements than in the embodiment of the Prior Patent where theopposite direct connection was provided. Although the pressuresgenerated in the pumps 98 and 157 are additive to produce a sum pressureat the generator 80, each pump is operating independently under theinfluence of an independent motive system.

In FIG. 11, the motor 152' drives a solution pump 98'. The secondsolution pump .[.157' .Iadd.157" .Iaddend.is driven in reciprocatingmotion by an energy recovery device 158' connected to the pressureexpansion valve 87. In this alternative embodiment the strong solutionenters the pumps 98' and .[.157' .Iadd.157" .Iaddend.at the same suctionpressure. However, on the discharge side, the outlets from the pumps arecombined at the same pressure. The flow to the generator 80 is the sumof the two flows.

In either the embodiment of FIG. 10 or the embodiment of FIG. 11sufficient energy recovery is provided to contribute significantly to.[.the.]. increase the COP to a range of about 0.8 in cooling mode.

Referring to FIG. 12, an energy recovery motor combining components 157and 158 is shown as energy recovery means 350. Unit 350 is fed bysolution pump 98. The output of solution pump 98 is divided and passesthrough check valve means 351 and 352 to opposite ends of thereciprocating piston pump 350 comprising a cylinder 353 centrallydivided into chambers 354 and 355 by opposite ends of a reciprocatingpiston 356. Piston 356 divides the chambers 354 and 355 into secondchambers 357 and 358 respectively. Chambers 354 and 355 are providedwith outlets through check valve means 360 and 361 respectively. Checkvalve means are connected together to provide a connection to the firstprimary generator means 80.

Solution 85 at high pressure is provided to the second chambers 357 and358 respectively through control valves 362 and 363 respectively.Solution leaves the chambers 357 and 358 through control valves 364 and365 to the secondary generator 81. The control valves 362, 363, 364 and365 operate to time the admission of high pressure solution to thechambers 357 and 358 and cause the piston 356 to reciprocate raising thesolution pressure to the higher level requirements at the primarygenerator 80. Energy recovery through reciprocating motion and devicesof this type are available from the Recovery Engineering Inc. ofMinneapolis, Minn. The details of their construction and operation arenot a part of this invention.

It is herein understood that although the present invention has beenspecifically disclosed with the preferred embodiments and examples,modifications and variations of the concepts herein disclosed may beresolved to by those skilled in the art. Such modification andvariations are considered to be within the scope of the invention andthe appended claims.

We claim:
 1. An absorption refrigeration and/or heating system inconnection with a primary source of heat, a cooling or heating load, anda heat sink or secondary source, to selectively provide heat to orremove heat from the load, including components comprising:(a) amultiple effect generator means having multiple desorber components toapply the primary source of heat to an absorption solution paircomprising a highly volatile refrigerant, and an absorbent and to desorbrefrigerant from the pair; (b) a condenser means connected to themultiple desorber components of the generator means; (c) an evaporatormeans connected to the condenser means; (d) an absorber means connectedto the evaporator means; (e) a pump means connected between the absorbermeans and the generator means to transfer solution to the generatormeans at higher pressure; and (f) a heat transfer subsystem forconveying a working fluid .[.and.]. between the components and havingmultiple switchable valve means, including first, second and third valvemembers selectively switchable to convey transfer fluid:(i) in the.[.one.]. cooling mode, to cool the load by directing the working fluidbetween heat exchange with the condenser means, the absorber means, andwith a first heat exchanger in heat exchange relationship to the heatsink, while directing the working fluid between heat exchange with theevaporator means and a second heat exchanger in heat exchangerelationship with the load, or (ii) in the heating mode, to heat theload by directing the working fluid between heat exchange with thecondenser means the absorber means and the second heat exchanger in heatexchange relationship with the load, while directing the working fluidbetween heat exchange with the evaporator means, and the first exchangermeans in heat exchange with the load; and (g) a pump means connectedbetween the members of the second subsystem to convey the working fluidthrough the subsystem.
 2. A system according to claim 1 wherein theworking solution is an antifreeze mixture with a freezing point belowthe temperature of water.
 3. A system according to claim 2 wherein heatfrom the working solution is conveyed to a domestic water heating systemwhen the system is in the heating mode.
 4. A system according to claim 1wherein the working solution is conveyed from the absorber means to adomestic water heating system when the system is in the cooling mode. 5.A system according to claim 1 wherein an accumulator is provided in thesystem to adjust the refrigerant concentration in the absorptionsolution pair as a function of the operating condition in the system. 6.A system according to claim 5 wherein an accumulator is connectedbetween the evaporator means and the absorber to adjust the refrigerantconcentration and solution as a function of the operating condition inthe system.
 7. A system according to claim 6 wherein the concentrationis adjusted between about 46% and about 32% refrigerant.
 8. A systemaccording to claim 1 wherein the first valve means directs the workingfluid through the first heat exchanger means while the second valvemeans directs the working fluid through the second heat exchanger meansand the third valve means operates as a conduit, during both the heatingand the cooling modes.
 9. A system according to claim 8 wherein thethird valve means is selected to convey the working fluid from thecondenser to the first heat exchanger and from the second heat exchangerthrough the absorber means, in a mode to defrost the first heatexchanger.
 10. A system according to claim 9 wherein, in the defrostmode the first valve means is connected to convey the working fluidbetween the condenser and the first heat exchanger, and to convey theworking fluid from the second heat exchanger to the absorber; and thesecond valve means is connected to direct the working fluid from theabsorber to the second heat exchanger while flowing the working fluidfrom the evaporator to the first heat exchanger; and the third valvemeans is selected to direct the working fluid from the second heatexchange to the evaporator means and to direct the working fluid fromthe first heat exchanger to the condenser means.
 11. A system accordingto claim 1 wherein the highly volatile refrigerant is ammonia and theabsorbent is sodium thiocyanate.
 12. An absorption refrigeration and/orheating system in connection with a primary source of heat, a cooling orheating load, and a heat sink or secondary source, to selectivelyprovide heat to or remove heat from the load, comprising:(a) A multipleeffect generator means to heat an absorbent pair comprising anonvolatile sorbent and a highly volatile refrigerant which is solublein the absorbent, and to desorb refrigerant from the pair, the generatormeans comprising a first vessel constructed to receive sufficient heatof combustion to desorb refrigerant from the pair, and at least oneadditional vessel connected to the first vessel to receive therefrigerant and exchange heat from the refrigerant to the solution pairto further desorb refrigerant from the solution pair; (b) a condensermeans connected to the at least one additional desorber components ofthe generator means; (c) an evaporator means connected to the condensermeans; (d) an absorber means connected to the evaporator means; (e) apump means connected between the absorber means and the generator meansto transfer solution to the generator means at higher pressure; and (f)a heat transfer subsystem for conveying a working fluid between thecomponents and having multiple switchable valve means, including first,second and third valve members selectively switchable to convey transferfluid:(i) in the .[.one.]. cooling mode, to cool the load by directingthe working fluid between heat exchange with the condenser means, theabsorber means, and a first heat exchanger in heat exchange relationshipto the heat sink, while directing the working fluid between heatexchange with the evaporator means and a second heat exchanger in heatexchange relationship with the load, or (ii) in the heating mode, toheat the load by directing the working fluid between heat exchange withthe condenser means, the absorber means, and the second heat exchangerin heat exchange relationship with the load, while directing the workingfluid between heat exchange with the evaporator means, and the firstexchanger means in heat exchange with the load; and (g) a pump meansconnected between the members of the second subsystem to convey theworking fluid through the subsystem.
 13. A system according to claim 12wherein the solution pair from the first generator means is conveyed inheat exchange relationship with the solution being transferred to thefirst generator means by the pump means to recoup heat from the solutionpair, and the solution pair from the at least one second vessel ispassed in heat exchange relationship with the solution being transferredto the first vessel to recoup heat from the solution pair.
 14. A systemaccording to claim 13 wherein the generator means and the recuperatingmeans include a plurality of coiled tubes with the coils juxtaposed oneto the next in a generally annularly composite form with a generatormeans surrounding the source of heat and the recuperator meanssurrounding the generator means.
 15. An absorption refrigeration and/orheating system in connection with a primary source of heat, a cooling orheating load, and a heat sink or secondary source, to selectivelyprovide heat to or remove heat from the load, comprising:(a) a multipleeffect generator means to heat an absorbent solution pair comprising anonvolatile sorbent and a highly volatile refrigerant which is solublein the absorbent, and to desorb refrigerant from the pair, the generatormeans comprising a first vessel constructed to receive sufficient heatof combustion to desorb refrigerant from the pair, and at least oneadditional vessel connected to the first vessel to receive therefrigerant and exchange heat from the refrigerant to the solution pairto further desorb refrigerant from the solution pair; (b) a condensermeans connected to the at least one additional desorber components ofthe generator means; (c) an evaporator means connected to the condensermeans; (d) an absorber means connected to the evaporator means; (e) apump means connected between the absorber means and the generator meansto transfer solution to the generator means at higher pressure; and (f)a heat transfer subsystem for conveying a working fluid between thecomponents and having multiple switchable valve means, including first,second and third valve members selectively switchable to convey transferfluid:(i) in the .[.one.]. cooling mode, to cool the load by directingthe working fluid between heat exchange with the condenser means, theabsorber means, and a first heat exchanger in heat exchange relationshipto the heat sink, while directing the working fluid between heatexchange with the evaporator means and a second heat exchanger in heatexchange relationship with the load, or (ii) in the heating mode, toheat the load by directing the working fluid between heat exchange withthe condenser means, the absorber means, and the second heat exchangerin heat exchange relationship with the load, while directing the workingfluid between heat exchange with the evaporator means, and the firstexchanger means in heat exchange with the load; and (g) a pump meansconnected between the members of the second subsystem to convey theworking fluid through the subsystem. (h) recuperator means in theconnection between the pump means and the generator means and in theconnection between the generator means and the absorber means for theconduction of heat between the generator means and the absorber means,and for the conduction of heat between the solution pair flow streams atdifferent temperatures in the connections.